Dry kiln



Nov.4n l924 v 1,514,101 R. H. RAwsoNv ET Al.

ov. 4. 1924n 1,514,101

R. H.- RAWSON ET AL- DRY KILN w F'il ed July 2l, 192.1 3 Sheets-Shet A3 N l M n Y* 5% Patented Nov. 4, 1924..- 4

LSTATE isiaici RALPH H. RAWSON, F PORTLAND, OREGON, AND OLIVER M. GOSS, 0F SEATTLE, i

'WASHING-TON.

DRY KILN.

' Application ined July 21,

and a resident of the city of Seattle, county of King and State of Washington, have invented a certain new and useful Improvement in Dry Kilns, of which the following is a specification. A

Our invention relates Vparticularly to kilns designed for drying lumber'products and in this connection has for its particular object 15 the improvement of the methods of treatment and apparatus described in the Letters Patent of the United States to Harry Donald Tieinann, No. 1,268,180, dated June 4, 1918. Our practical experiments with vthe methods and means described in said Tiemann patent applied to the drying of lumber products of the Pacific Northwest have, shown that they are incomplete and insuiticient for the treatment of said lumberprducts in a commercial way. The object of our invention, stated in a general way, is to improve upon said Tiemann method and ap- I paratus in the following particulars First, to provide means whereby the spray lines are .kept free from condensation thereby preventing `the spraying of the moisture upon the lumber stacked in the kiln. Condensation in the spray lines is unavoidable and therefore without efficient means for removing the condensation the drying process is greatly impeded.

' Second, to provide means adapted to promote the maintenance of substantially equal temperatures thruout the length of the kiln.

We attain the rst mentioned object by connect-ing the ends of the spray lines with means, such as a trap, for collecting and removing condensation; the condensationdbeing discharged thru such means or carried back to' a hot well to be used over again as may be deemed expedient.' We furthermore provide spray pipes arranged in sets on opposite Vsides of the walls of the dryin chamber, each set being controlled by a va ve, and in connection therewith provide means operating said valves so as to throw one set' of spray pipes out of action when the other set is thrown into action; and the said valve operating means may be further supplewhen the valve of the other set is open; t is 1921. Serial No. 486,557.

niented by time controlled automatic means whereby the valve operating means are automatically thrown into action.

We attain the second object by the following arrangements used singly or preferably in combination, namely:

(a) By roviding heating coils having greater radiating surface at a point remote from the inlet of said heating fluid than at such inlet; and we also introduce the heating Huid .at a point centrally between the ends of the drying chamber of thekiln.

( By providing supplemental heating ycoils at that point where the drying uid A circulated in the rst mentioned or primary heating coils tends to attain a temperature relatively lower than` the other heating coils in the drying chamber.

(c) By providing a drain header with which the heating coilsare connected and by admitting heating duid into such 'header above the level of collected condensation. In this way the drying process is greatly promoted andthe results will be uniform and certain. 4

A further object of our invention isA to provide simple devices which Vwill eciently operate to produce the results yabove mentioned and `tend to generally promote the drying process. l

Such devices are illustrated in the accompanying drawings, which diagrammatically represent a dry kiln provided with said devices, namely:

F ig. 1 is a longitudinal section.A thru our improved dry Lkiln;

Fig. 2 is a plan section taken on the plane represented by the lines 2--2 in `Fig. 1;

Fig. 3 shows another diagrammatic section of a dr;r kiln embodying our improved means, the arrangement of whieh is somewhat differentv than as shown in Flg; l;

Fig. 4 is a plan section taken on t e plane indicated by the line 4--4 of Fig. 3; Y

Eig. -5 is a transverse section on the plane indicated by the lines 5-5 of Fig. l; l

Fig. 6 diagrammatically represents the valves controlling the two sets of spray pipes and the means for operating these valves so as to close the valve of one set of Aspray p1 es -gure also diagrammatically shows the temperature controller, or in other words, the valve whereby is controlled the amount of steam or other heating fluid admitted into the heating coils and; Fig. 7 shows a modiiication and detail of construction hereinafter described.

As Will be noted, all the views are foreshortened, both verticallyand horizontally, and the longitudinal sections also represent that the kiln has a slope towards its lett end.

Referring to the drawings, the heating apparatus and devices for regulating the' circulation are contained in a drying chamber, a. The lumber is piled on trucks (not shown) which run on rails R, supported by posts b, the lumber being piled flatwise or vertically as preferred.

Suspended from the side Walls of the drying chamber are yheating pipes D, into which is admitted live steam thru a drying header F, as in Fig. 1, or F in Fig. 3, the steam coming from' its-source thru a steam main, as Z in Fig. 6and thru pipes These pipes on the side Walls terminate in drip headers, D, which are locatedat low points in. 'the drying chamber at one or both ends. The condensed steam accumulates in vthese headers and may be drawn-off by any convenient means.

Also suspended from the ceiling of the drying chamber are rows of additional heating pipes, C, which begin at an inlet header, and terminate in a drain header H as shown in Fig. 1, or by H in Fig. 3. From these drain headers the condensatien is piped out of the kilnfinto a trap or other meansy for removing condensation, not shown'.

Located below the lumber pile or piles, are heating pipes C and C2 which have their beginning atheaders G. These pipes, C and 2, terminate in drain-headers I, from which the condensation is removed as mentioned above. The steam is admitted to the inlet header, G and Gr', thru pipes M, as'described above. l

If desired, live steam may be 'admitted into headers. D, at a point E which is just above the level of the condensation in such headers. This arrangement is adapted to raise the temperature at this end of the drying chamber and thus produce equal tem- A peratures thruout its length. l

In Fig.. 2 1s shown that the number o heating pipes C is increased at such a point where the temperatures tend to be lower than at the inlet end, for example, as at C2;

the increased heating surface tending brlng the temperature up and thereby equallzlng the conditions thruout the length of the drying chamber. The same eii'ect could also be obtained by'coupling the pipes C with pipes of larger cross section located at C2,`as illustrated by C3 in Fig. 7.

Arranged above and below the heating pipesDQare spray pipes, A on one side wall, and A on the opposite side wall. These pipes emit steam' at high 'pressure into the drying chamber. In case .the lumber is piled tlatwise, the direction of the steam jets is as indicated in Fig. 5, but if the lumber is vertically piled the courses ot' the lower pipes, A' and A', may be given a quarter turn, so as to force the heating pies D. Under such circumstances the upper course of spray pipes should be turned oi to prevent the formation of .counter currents. v i

The spray pipes A and A terminate at a low point in the drying chamber and are piped to a trap B located outside the chamber. The trap B may be of such constructhe jets of steam upward over tion that the condensation is removed autoe matically as it accumulates in the trap or drop pipi?, A2, without Wasting the steam. There being several well knownv commercial makes oi trapspf this type, no description C is necessary here. It is to be noted that the steam spraying orifices of the sprayvaporsv are 4released through said orifices, while the condensations collecting in said spray pipes are conducted by said troughlike pipe portions to said trap.

Located Without the drying chamber are means for controlling the temperature in the drying chamber, and for controlling the steam` entering the spray pipes A and A, see'Figs. 5 and 6. f

V is a direct act-ing valve so constructed that a spring causes the valve to remain open unless pressure is exerted on the valve stem. V represents a reverse acting valve of such construction that a spring causes it to remain closed until pressure is exerted on its stem. A time arrangement, indicated by V3, Fig. 6, is provided to operate at certain intervals to admit fluid under' pressure thru pipe V2 on the stems of valves V and V and thus, by reason'of the construction of said valves as mentioned above, V is closed and V is opened. 5 are hand valves.

T, F ig.` 6, is a valve with a diaphragm top which is controlled by a iuid under pres- A thermostatic Huid is contained in a tube, T3, Fig. 5, which terminates in a time device as indicated diagrammatically by T2. The thermostatic fluid, expanding with a rise in temperature within the drying chamber, admits Huid under pressure into tube T which exerts pressure on the top of dialeading to said trap B. Hence the steam diagrammatically, a pressure regulator which makes it possible to carry a constant.

steam pressure in the heating coils.

U is an auxiliary cutoff valve, which may be used to shut off all steam connections to the drying chamber. The described'valves are l easily obtainable commercially and .therefore description of thcirconstruction and operation is unnecessary. See for eXample catalogue 460 of C. J. Tagliabue Com with C, C and coils D on the oppositev Wall thru their respective headers G, G", and F and F.

We claim: A,

l. In a dry kiln, av horizontally disposed steam spray pipe sloped to drain the condensation Within it to a -low point, and a trap connected with said lov:r point adapted to remove the condensation automatically as it accumulates; the spray orifices of said spray pipe being so located as to leave an u nperforated trough-like portion at the bottom of the spray pipe, whereby the vapors Within the latter are released through said orifices While the condensation collecting in 4 the spray pipe is conducted by the troughlike portion of the latter to said trap.

2. Ina dry kiln, spray pipes arranged in sets, each set controlled by a valve, and means adapted to cause the opening of, the valves of one set of spray pipes simultaneously with the closing of the valves of the other set.

3. In a dry kiln, spray pipes arranged in sets, each'set controlled by a valve, and time controlled,` automatic;` means adapted to cause the opening of the valves of one set of spray pipes simultaneously with the closing of the valves of the other set. Y

4. In a dry kiln, spray pipes arranged to drain to-a low point, said spray pipes being arranged in sets, each set controlled by a valve, a trap of the character described connected with said low point, and means adapted to cause the opening of the valves' of one set of spray pipes simultaneously with the closingof the valves of the other set. f

pipes simultaneously with the closing of the valves of the other set.

6.' In a dry kiln, primary heating coils-Li,

adapted to provide greater radiating surface at a point remote from the inlet of the heating fluid than at such inlet, andsupplemental heating coils located at a point Where the heating fluid in the primary heating coils tends to attain a temperature relatively lower than at other ypoints in the dry kiln.

7. In a' dry killnheating coils, a drain header with which the heating coils are connected, and a connection from thesource of heating Huid entering said header abovethe level of condensation therein'.

8. In a dry kiln, heating coils, and means for automatically regulating the amountot coils, thereby to regulatetheir temperature, and thereby control the humidity.4

9. In a dry kiln, heating coils, neans for automatically regulating the amount of heating uid admitted into said heating coils, thereby to' regulate their temperature, and thereby control the humidity', a drain header with Which the heating coils are connected, and a connection from the source of heating iiuid entering said header above the level of condensation therein.

10. In a dry kiln, spray pipes arranged to drain to a low point, a trap of the character described connected with said loW point.. and heating coils.

11. In a dry kiln, spray pipes arranged to drain to a low point, a trap of the char` acter described connected with 'said low point, and heating coils adapted to provide greater radiating surface at a point remote from the inlet of the heating fluid than an at such inlet.

`heating uid admitted into said heating 12. In a dry kiln, spray pipes arranged to drain to a low point, avtrap of the characterdescribed connected with said vlon1 point, primary heating coils adapted to provide greater radiating surface at a point remote from the inlet of the heating Huid than at such inlet, and supplemental heating coils located at a point where the ,heating uid in the primary heating coils tendsf to attain a temperaturei relatively lower than at other points in the dry kiln.

13. In aj dry kiln. spray plpes arranged to drain to a low point, a trap of the character described connected with said low point, heating coils, and means for automatically regulating the amount of heating Huid admitted into said heating coils, thereby to regulate their temperature, and thereby control the humidity.

14. 'In a dry kiln, spray pipes arranged to drain to a low point, a trap of the character .described connected with said low point, heating coils, a drain header with which the heating coils are connected, and a connection from the source of heating uid densation` therein.

densation therein.

' 15. In a dry kiln, spray pipes varranged to drain to a low point, a trap of the character described connected 'with Vsaid ylow point, heating coils, means for automatically regulating the amount of heating Huid admitted into vsaid heating coils, thereby to regulate their temperature, and thereby control the humidity, a drain header With Which the'heating coils lare connected, and a connection from the source of heating fluid entering said header above the level of con- 16. 'In -a dry kiln, lspray pipes arranged to`drain to a ovv point, a trap of the character described connected .with said low point, means adapted to cause the opening of the valves of one set of spray pipes simultaneously with the closingof the valves of the other-set, heating coils, means for automatically regulating the amount of heating Huid admitted into said heating coils, thereby to regulate their temperature, and -thereby control the humidity a drain header With'vwhich the heating coils are connected, and a connection yfrom the source of yheating fluid entering said header above the level of condensation therein.

17. In a dry kiln, spray pipes arranged to.

drain to a lowpoint, said spray pipes being arranged in sets, each set controlled by a valve, a trap of the character described connected with said low point, means adapted to cause the openino of the valves o one set of spray pipes simultaneously Wit the closing of the valves of the other set, primary -heating coils adapted' to provide` greater radiatipg surface at a point remote from the inlet of the heating luid than at such inlet, supplemental heating coils located at Ia point Where the heating Huid in the primary heating coils tends'to attain a temperature relatively lower than atA other points in the dry kiln, means for automatically regulating the amount of heating fluid admitted into said heating coils,

' there-by to regulate their temperature, and

vthereby control the humidity, a drain header with which the heating coils are connected, and a connection from the source of heating fluid entering said'header above the level of condensation therein.m

drain to a'loW point, said spray pipes being arranged in sets, each set controlled by a valve, a trap of the characterdescribed connected with said loW point, time controlled, automatic means adapted to cause the opening of the valves of one set of spray pipes simultaneously with the closing of the valves of thel other set, primary heating coils adapted to provide greater radiating surface at a point remote from theinlet of the heating fluid than at such inlet, supplemental heating coils located at a point Where the heating'luid in the primary heatingcoils tends to attain a temperature relatively lower than at other points in the dry kiln, means for automatically regulating the 18. In a dry kiln, spray pipes arranged tov amount of heating fluid admitted into said heatingI coils, thereby to regulate their temheating coils are connected, and a connec- 0tion from the source of heating Huid entering said header above the level of condensation therein.

19. In a-dry kiln, a system of spray pipes, connected to a source of drying Huid, and time controlled means for causing the automa'tic reversal of the direction of steam sprays im the kiln by closing one valve and opening theiother valve simultaneously.

20. In a dry kiln, a system of spray pipes connectedv at separated points to a source of drying Huid, `and time controlled means for causing the automatic reversal of the direction of the steam sprays in the kiln by closing one 2valve and opening the other valve simultaneously.

21,. In a dry kiln, a system of spray pipes connected at separated points to a source of drying Huid, a valve in each of said connections, and time' controlled, automatic means for opening Vand closing said valves alternately With each other.

22. In a dry kiln, a system of spray pipes, connected at separated points to a source of drying fluid, -a valve in each of said connections, time controlled, automatic means for opening and closing said yalves alternately with each other, auxihary cut off valves -in said connections, and a by-pass around one of said valves.

RALPH H. RAWSON. OLIVER P. M. GOSS'. 

